diff --git a/boards/px4/raspberrypi/cmake/upload.cmake b/boards/px4/raspberrypi/cmake/upload.cmake
index f0ee765a62..ce0472b8a7 100644
--- a/boards/px4/raspberrypi/cmake/upload.cmake
+++ b/boards/px4/raspberrypi/cmake/upload.cmake
@@ -31,7 +31,7 @@
 #
 ############################################################################
 
-if($ENV{AUTOPILOT_HOST})
+if(DEFINED ENV{AUTOPILOT_HOST})
 	set(AUTOPILOT_HOST $ENV{AUTOPILOT_HOST})
 else()
 	set(AUTOPILOT_HOST "raspberrypi")